Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Silicon solution could lead to a truly long-life battery

11.05.2005


New devices may provide power for decades



Using some of the same manufacturing techniques that produce microchips, researchers have created a porous-silicon diode that may lead to improved betavoltaics. Such devices convert low levels of radiation into electricity and can have useful lives spanning several decades.

While producing as little as one-thousandth of the power of conventional chemical batteries, the new "BetaBattery" concept is more efficient and potentially less expensive than similar designs and should be easier to manufacture. If the new diode proves successful when incorporated into a finished battery, it could help power such hard-to-service, long-life systems as structural sensors on bridges, climate monitoring equipment and satellites.


The battery’s staying power is tied to the enduring nature of its fuel, tritium, a hydrogen isotope that releases electrons in a process called beta decay. The porous-silicon semiconductors generate electricity by absorbing the electrons, just as a solar cell generates electricity by absorbing energy from incoming photons of light.

Supported by grants from the NSF Small Business Innovation Research (SBIR) program, a multi-disciplinary team of researchers from the University of Rochester, the University of Toronto, Rochester Institute of Technology and BetaBatt, Inc. of Houston, Texas, describe their new diode in the May 13 issue of Advanced Materials.

Researchers have been attempting to convert radiation into electricity since the development of the transistor more than 50 years ago. Mastering the junctions between relatively electron-rich and electron-poor regions of semiconductor material (p-n junctions) led to many modern electronic products.

Yet, while engineers have been successful at capturing electromagnetic radiation with solar cells, the flat, thin devices have been unable to collect enough beta-decay electrons to yield a viable betavoltaic device.

The BetaBatt will not be the first battery to harness a radioactive source, or even the first to use tritium, but the new cell will have a unique advantage - the half-millimeter-thick silicon wafer into which researchers have etched a network of deep pores. This structure vastly increases the exposed surface area, creating a device that is 10 times more efficient than planar designs.

"The 3-D porous silicon configuration is excellent for absorbing essentially all the kinetic energy of the source electrons," says co-author Nazir Kherani of the University of Toronto. Instead of generating current by absorbing electrons at the outermost layer of a thin sheet, surfaces deep within these porous silicon wafers accommodate a much larger amount of incoming radiation. In early tests, nearly all electrons emitted during the tritium’s beta decay were absorbed.

There were a number of practical reasons for selecting tritium as the source of energy, says co-author Larry Gadeken of BetaBatt - particularly safety and containment.

"Tritium emits only low energy beta particles (electrons) that can be shielded by very thin materials, such as a sheet of paper," says Gadeken. "The hermetically-sealed, metallic BetaBattery cases will encapsulate the entire radioactive energy source, just like a normal battery contains its chemical source so it cannot escape."

Even if the hermetic case were to be breached, adds Gadeken, the source material the team is developing will be a hard plastic that incorporates tritium into its chemical structure. Unlike a chemical paste, the plastic cannot not leak out or leach into the surrounding environment.

Researchers and manufacturers have been producing porous silicon for decades, and it is commonly used for antireflective coatings, light emitting devices, and photon filters for fiber optics. However, the current research is the first patented betavoltaic application for porous silicon and the first time that 3-D p-n diodes have been created with standard semiconductor industry techniques.

"The betavoltaic and photovoltaic applications of 3-D porous silicon diodes will result in an exciting arena of additional uses for this versatile material," says co-author Philippe Fauchet of the University of Rochester.

"This is the first time that uniform p-n junctions have been made in porous silicon, which is exciting from the point of view of materials science," says Fauchet. For example, because of its characteristics and photon sensitivity, each diode pore could serve as an individual detector, potentially creating an extremely high-resolution image sensor.

"The ease of using standard semiconductor processing technology to fabricate 3-D p-n junctions was surprising," adds co-author Karl Hirschman of the Rochester Institute of Technology. That manufacturing ease is an important breakthrough for increasing production and lowering costs, and it makes the device scalable and versatile for a range of applications.

"The initial applications will be for remote or inaccessible sensors and devices where the availability of long-life power is critical," says Gadeken.

The BetaBattery may prove better suited to certain tasks than chemical batteries when power needs are limited. The structures are robust--tolerant to motion and shock, and functional from -148° Fahrenheit (-100° Celsius) to 302° F (150°C)--and may never have to be changed for the lifetime of the device.

Josh Chamot | EurekAlert!
Further information:
http://www.nsf.gov

More articles from Power and Electrical Engineering:

nachricht Microhotplates for a smart gas sensor
22.02.2017 | Toyohashi University of Technology

nachricht Positrons as a new tool for lithium ion battery research: Holes in the electrode
22.02.2017 | Technische Universität München

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Microhotplates for a smart gas sensor

22.02.2017 | Power and Electrical Engineering

Scientists unlock ability to generate new sensory hair cells

22.02.2017 | Life Sciences

Prediction: More gas-giants will be found orbiting Sun-like stars

22.02.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>